The MFMailComposeViewController class, a UINavigationController, allows the user to edit a mail message. The user can attempt to send the message there and then, or can cancel but save a draft, or can cancel completely. Before using this class to present a view, call canSendMail; if the result is NO, go no further, as a negative result means that the device is not configured for sending mail. A positive result does not mean that the device is connected to the network and can send mail right now, only that sending mail is generally possible with this device; actually sending the mail (or storing it as a draft) will be up to the device’s internal processes.

To use MFMailComposeViewController, instantiate it, provide a mailComposeDelegate (not delegate), and configure the message to any desired extent. The user can later alter your preset configurations, at which time the message details will be out of your hands. Configuration methods are:

Typically, you’ll show the MFMailComposeViewController as a presented view controller. This approach works equally well on the iPad (use UIModalPresentationFormSheet if a full-screen presentation feels too overwhelming).

The delegate (MFMailComposeViewControllerDelegate) will receive the message mailComposeController:didFinishWithResult:error: describing the user’s final action, which might be any of these:

Dismissing the presented view is up to you, in the delegate method.

Here’s a minimal example:

- (IBAction)doMail:(id)sender {
    BOOL ok = [MFMailComposeViewController canSendMail];
    if (!ok) return;
    MFMailComposeViewController* vc = [MFMailComposeViewController new];
    vc.mailComposeDelegate = self;
    [self presentViewController:vc animated:YES completion:nil];
}

-(void)mailComposeController:(MFMailComposeViewController *)controller
        didFinishWithResult:(MFMailComposeResult)result
        error:(NSError *)error {
    // could do something with result/error
    [self dismissViewControllerAnimated:YES completion:nil];
}

The MFMessageComposeViewController class is a UINavigationController subclass. Before using this class to present a view, call canSendText; if the result is NO, go no further. The user has no option to save an SMS message as a draft, so even if this device sometimes can send text, there’s no point proceeding if the device can’t send text now. However, you can register for the MFMessageComposeViewControllerTextMessageAvailabilityDidChangeNotification in the hope that the device might later be able to send text; if the notification arrives, check its MFMessageComposeViewControllerTextMessageAvailabilityKey.

To use MFMessageComposeViewController, instantiate the class, give it a messageComposeDelegate, configure it as desired through the recipients (phone number strings) and body properties, and show it as a presented view controller. The user can later alter your preset configurations, at which time the message details will be out of your hands.

The delegate (MFMessageComposeViewControllerDelegate) will receive the message messageComposeViewController:didFinishWithResult: with a description of the user’s final action, which might be any of these:

Dismissing the presented view is up to you, in the delegate method.

Here’s a minimal example:

- (IBAction)doMessage:(id)sender {
    BOOL ok = [MFMessageComposeViewController canSendText];
    if (!ok) return;
    MFMessageComposeViewController* vc = [MFMessageComposeViewController new];
    vc.messageComposeDelegate = self;
    [self presentViewController:vc animated:YES completion:nil];
}

-(void)messageComposeViewController:(MFMessageComposeViewController*)controller
        didFinishWithResult:(MessageComposeResult)result {
    // could do something with result
    [self dismissViewControllerAnimated:YES completion:nil];
}

In iOS 6, the interface for letting the user construct a Twitter post is SLComposeViewController, part of the Social framework (superseding TWTweetComposeViewController and the Twitter framework). Twitter, together with Facebook and Weibo, are represented by constant strings. You’ll use a class method to learn whether the desired service is available; if it is, you can instantiate SLComposeViewController for that service and present it as a presented view controller.

Instead of a delegate, SLComposeViewController has a completionHandler. Set it to a block taking one parameter, an SLComposeViewControllerResult. In the block, dismiss the view controller.

Here’s a minimal example:

BOOL ok =
    [SLComposeViewController
        isAvailableForServiceType:SLServiceTypeTwitter];
if (!ok) return;
SLComposeViewController* vc =
    [SLComposeViewController
        composeViewControllerForServiceType:SLServiceTypeTwitter];
if (!vc) return;
vc.completionHandler = ^(SLComposeViewControllerResult result) {
    // could do something with result
    [self dismissViewControllerAnimated:YES completion:nil];
};
[self presentViewController:vc animated:YES completion:nil];

You can also, with the user’s permission, gain secure access to the user’s Twitter account information (or Facebook, or Weibo) through the ACAccountStore class (part of the Accounts framework). Using this, along with the SLRequest class, your app can construct and post a message directly, without passing through the message composition interface; see Apple’s Tweeting example. The ACAccountStore class can manipulate accounts in other ways as well.